Magnetic switches find widespread use, such as, for example, in burglar alarm systems where the actuating element for the switch does not directly come in contact with the switch. Typically, the switch is mounted on one fixed member such as a doorway or a window jamb, while the magnetic actuating element is fastened to a movable member such as the window, door or the like. The switch is interconnected to the burglar alarm system. When the window or door is moved, the switch contacts move from either a normally open or normally closed position to the opposite position, thus providing an actuating signal for the alarm system.
The prior art contains numerous types of magnetic switches which are typically held in plastic housings. Some of the prior art switches utilize reed contacts, while others utilize mechanical contacts. Unfortunately, these devices suffer from many disadvantages which detract from their performance, reliability and durability. For example, the reed switches can easily be defeated by using an additional magnet to hold the contact in a closed position. Utilizing the additional magnet, an unauthorized intruder can prevent the contact switches from moving while still opening the door, window, or the like. The mechanical contact switches suffer from failure after continued usage. Such prior art mechanical switches generally utilize leaf springs or flexed armatures. After continued usage, constant bending and flexure weakens the metal contacts and either produces complete device failure or unreliable performance.
In order to improve the performance of magnetic switches, complex arrangements have been incorporated to improve their reliability and durability. These complex arrangements include the use of bifurcated members having separate contacts and armatures which consecutively contact each other upon application of a magnetic force. Such complex arrangement is described in U.S. Pat. No. 3,676,811. Other types of magnetic switches control the flux pattern produced by permanent magnets, as described in U.S. Pat. No. 3,226,506 or U.S. Pat. No. 3,487,346. While these aforementioned devices may improve performance, they also increase the cost of manufacture and limit the extent of use of a particular device to unique situations. The switches described do not have the flexibility to be utilized in various types of situations and various types of burglar alarm systems.